defmodule Microwaveprop.BeaconMonitors.BeaconMonitor do
  @moduledoc """
  A beacon monitor is a physical SDR-based hardware unit assigned to a
  user. The unit runs the `propmonitor` client which reports beacon
  reception measurements back to Microwaveprop.

  Each monitor has a unique random token the client uses to authenticate
  its measurement uploads.
  """

  use Ecto.Schema

  import Ecto.Changeset

  alias Microwaveprop.Accounts.User
  alias Microwaveprop.Beacons.Beacon

  @primary_key {:id, :binary_id, autogenerate: true}
  @foreign_key_type :binary_id
  schema "beacon_monitors" do
    # Identity / label
    field :name, :string
    field :token, :string
    field :last_seen_at, :utc_datetime

    # Hardware identity
    field :hardware_type, :string
    field :hardware_id, :string
    field :firmware_version, :string

    # Antenna / installation
    field :antenna_type, :string
    field :antenna_gain_dbi, :float
    field :lat, :float
    field :lon, :float

    # Active configuration (admin + assigned user can change)
    field :config_frequency_hz, :integer
    field :config_integration_s, :integer
    field :config_mode, :string

    # Relationships
    belongs_to :user, User
    belongs_to :beacon, Beacon
    belongs_to :assigned_by, User

    timestamps(type: :utc_datetime)
  end

  @type t :: %__MODULE__{}

  @doc """
  General changeset — allows basic fields. Context-level functions
  enforce which caller-role can set which fields.
  """
  @spec changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
  def changeset(monitor, attrs) do
    monitor
    |> cast(attrs, [:name])
    |> validate_required([:name])
    |> validate_length(:name, min: 1, max: 100)
  end

  @doc """
  Provisioning changeset — used by admins to register new hardware.
  Casts all hardware-identity, antenna, and assignment fields.
  """
  @spec provision_changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
  def provision_changeset(monitor, attrs) do
    monitor
    |> cast(attrs, [
      :name,
      :hardware_type,
      :hardware_id,
      :firmware_version,
      :antenna_type,
      :antenna_gain_dbi,
      :lat,
      :lon,
      :user_id,
      :assigned_by_id
    ])
    |> validate_required([:name])
    |> validate_length(:name, min: 1, max: 100)
    |> validate_length(:hardware_type, max: 100)
    |> validate_length(:hardware_id, max: 255)
    |> validate_length(:firmware_version, max: 50)
    |> validate_length(:antenna_type, max: 100)
    |> validate_number(:antenna_gain_dbi, greater_than_or_equal_to: -20, less_than_or_equal_to: 60)
    |> validate_number(:lat, greater_than_or_equal_to: -90, less_than_or_equal_to: 90)
    |> validate_number(:lon, greater_than_or_equal_to: -180, less_than_or_equal_to: 180)
    |> foreign_key_constraint(:user_id)
    |> foreign_key_constraint(:assigned_by_id)
  end

  @doc """
  Configuration changeset — used by admins and assigned users to update
  what the monitor is listening for.
  """
  @spec config_changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
  def config_changeset(monitor, attrs) do
    monitor
    |> cast(attrs, [:name, :beacon_id, :config_frequency_hz, :config_integration_s, :config_mode])
    |> validate_required([:name])
    |> validate_length(:name, min: 1, max: 100)
    |> validate_length(:config_mode, max: 50)
    |> validate_number(:config_frequency_hz, greater_than: 0)
    |> validate_number(:config_integration_s, greater_than_or_equal_to: 5, less_than_or_equal_to: 3600)
    |> foreign_key_constraint(:beacon_id)
  end
end